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Old 1st February 2014, 12:55 AM   #161
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Originally Posted by still4given View Post
Hi Patrick,

You can see the specs here.

I'm not sure which are the smoothing caps. I am attaching a close up of the unit.

Blessings, Terry
The ones with the coils in between them and I already saw the capacitance thanks the pic

Last edited by meanman1964; 1st February 2014 at 12:57 AM.
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Old 3rd February 2014, 03:28 PM   #162
Sheldon is offline Sheldon  United States
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Jason,

On thing I'm curious about: On your schematic, the current for the feedback path is injected between the 100R and 2.2k resistor. On all the others, the injection node is between the cap to the common and the 100R. That would imply a difference in the impedance at that node. Not sure the significance but I looked around and couldn't fine any explanation for choosing one over the other.

Sheldon

Last edited by Sheldon; 3rd February 2014 at 03:31 PM.
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Old 3rd February 2014, 07:22 PM   #163
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Sheldon,

The current injection point doesn't seem to make much difference with respect to performace. It simmed with slightly (and I mean very marginal) less distortion so I thought I'd give it a try. There is slightly less DC voltage on the FB caps as well.

The choice is deliberate.
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Old 3rd February 2014, 09:58 PM   #164
Sheldon is offline Sheldon  United States
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Originally Posted by jkuetemann View Post
Sheldon,

The current injection point doesn't seem to make much difference with respect to performace. It simmed with slightly (and I mean very marginal) less distortion so I thought I'd give it a try. There is slightly less DC voltage on the FB caps as well.

The choice is deliberate.
Thanks,

I realized that after I posted. With a very high impedance source, the difference made by a 100R resister on either side would be proportionally insignificant.

Sheldon
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Old 3rd February 2014, 11:17 PM   #165
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Default All deliveries fulfilled

Thanks folks, every package reached its destination!

still4given - 2 - Delivered
ivanlukic - 2 - Delivered
quan - 2 - Delivered
triplej - 2 - Delivered
baswamin - 2 - Delivered
potepuh - 2 - Delivered
spind - 2 - Delivered
brianco - 2 - Delivered
Sheldon - 2 - Delivered

Sounds like a few of you have / may be starting builds, so if you have any comments, questions or suggestions feel free to throw it out there. Pics are good too .
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Old 4th February 2014, 09:49 PM   #166
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I'm forging ahead with some changes to the design and will post information when I have it. I'm open to suggestions to incorporate into the next iteration of the design should someone have input. I will add to post #1 to hopefully keep things organized and accessible over time.

For now I'm going to put up a ZIP of the Gerber and Excellon files of the current version, should someone choose to have additional ones made for themselves.
Attached Files
File Type: zip VSSAv2revB.zip (35.5 KB, 155 views)
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Old 5th February 2014, 12:04 AM   #167
Sheldon is offline Sheldon  United States
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I'd suggest a Jfet ccs. Three parts max - voltage dropping resistor (if needed), FET, trimpot. Same parts used for both rails. No current shunted to bias the CCS. Something simple and common like J112 would work fine.

Sheldon
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Old 5th February 2014, 12:35 AM   #168
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I need to do some more reading. I found some articles by Walt Jung pertaining to the subject of CCS types for audio. My only reservation about JFETs is what looks like continually dwindling availability and wide variances in parameters.
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Last edited by jkuetemann; 5th February 2014 at 01:03 AM. Reason: Changed comment.
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Old 5th February 2014, 01:31 AM   #169
BYRTT is online now BYRTT  Denmark
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Quote:
Originally Posted by jkuetemann View Post
I need to do some more reading........
Don't no if it helps and save some labour. Links to member nikosokey's VSSA based on your PCB's Jason. He used fets/CSS and TLVH431, in fact looks near to LC's VSSA except layout/component choice, maybe PM nikosokey.
VSSA Lateral MosFet Amplifier
VSSA Lateral MosFet Amplifier
VSSA Lateral MosFet Amplifier
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Old 5th February 2014, 02:51 AM   #170
Sheldon is offline Sheldon  United States
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Originally Posted by jkuetemann View Post
I need to do some more reading. I found some articles by Walt Jung pertaining to the subject of CCS types for audio. My only reservation about JFETs is what looks like continually dwindling availability and wide variances in parameters.
They do vary more than transistors, but it's really not an issue here, as each leg is individually adjusted anyway. Not hard to select parts if you wish, and the variance is typically much less within a lot than the specs. suggest. You still get, with fewer parts, higher impedance. I might add a gate resistor to the list of parts, but that's it.

Sheldon
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